1. Field of the Invention
The present invention relates to a battery clamping device for pressing and clamping rectangular parallelepiped batteries, and a battery heating device, a battery drying device, a battery cooling device each provided with the same battery clamping device, and method for manufacturing a battery using the same battery clamping device or the same battery drying device.
2. Description of Related Art
In recent years, a rechargeable/dischargeable battery such as a rectangular parallelepiped lithium ion secondary battery (hereinafter referred to as just battery also) has been used as a driving power source of a vehicle such as a hybrid vehicle, electric vehicle and a portable electronic apparatus such as notebook personal computer, video camcorder. In manufacturing or test of such a battery or manufacturing of a battery pack, there is a case where a plurality of batteries is desired to be clamped. For example, a case of drying the inside of a case of a battery prior to pouring of electrolyte therein (non-sealed battery described below), a case of performing initial charge of a battery prior to the initial charge (not-initially charged battery described below), and a case of performing high-temperature aging of a battery after the initial charge can be mentioned. As a jig (device) for use in this case, Japanese Patent Application Publication No. 2012-190620 (JP 2012-190620 A) has disclosed a battery restraining device (battery clamping device described below) configured to restrain a plurality of rectangular parallelepiped batteries and spacers stacked alternately while applying vibration by using a fixed press head and a movable press head.
However, if the stack is restrained strongly using the above-described battery restraining device (battery clamping device), a plurality of batteries in the stack is pressed strongly in the stacking direction. Accompanied by this, sometimes the battery might swell in a direction perpendicular to the stacking direction (i.e., height direction or width direction of battery) so that in some cases, it might undergo permanent deformation. Particularly, if the battery is configured so that an opening in its bottomed square-section cylindrical battery case main body is sealed with a sealing lid having a larger thickness than that of the bottom portion of the battery case main body, the bottom face of the battery is more likely to swell than the sealing lid. As a result, the height from the bottom face of the battery to the sealing lid is increased. On the other hand, because the extent of the swelling of the bottom face which occurs in the plurality of the batteries after compression differs depending on each battery, when these batteries are assembled into a battery pack with their bottom faces as a standard level, deflection occurs in the position of the sealing lid or an external terminal member provided on the sealing lid among respective batteries with respect to the height direction from their bottom faces. As a result, such an undesirable effect that the external terminal members of adjacent batteries cannot be joined together easily when connecting them using a flat bus bar may occur.